ok shit dont make sense

[brent379]

Ok I've been racking my brain for a few months now trying to figure this out and can't understand it.

I look at people's builds threads...see vids on YouTube....and people will be running say a couple tens...mainly a couple twelves...with ONE 6 maybe 8 inch aero port with a massive flare and they have good luck with it! No chuffing or anything! When I first ran 2 sd 10s isobaric...I used one 6 inch aero and it failed horribly. Had 80mph winds coming out of the box. I only used about a 1 inch flare tho.

So I guess my main question is...how can these people with 12s on a good 1-2000 rms use only 1 six inch aero port! Does a huge flare like that really make that big of a difference??? I was just playing around on winisd and if I were to take my two sd 10s.... put them I'm a 4 cube box...supposedly it would take a single 9 inch aero to Keep port velocity down...and even then it's still at over 20m/sec!!! I don't get it... and yes I know 4 cubes is wayyyy bigger then what those tens need but I was just experimenting and a smaller box makes even higher port velocity.

Other question is how the Hell do you use that program called flare-it???? I can't figure it out. Where do you get the "required velocity" port numbers from???

[Skullz]

As long as the port does not restrict the flow of air, the velocity even at high speeds is ok until you hear the distinct sound of chuffing which is now restricting the flow and not doing what you want the port to do. Simple test to understand port velocity, close your lips until you have a hard time breathing and you'll find that you can breathe better with your lips closed pretty far, also watch people as they pant trying to get their breath and you'll see the same thing even though your could open your mouth all the way.

Velocity is a good thing.

[Skullz]

The thing with ports is to give the port enough area for the number of subs your going to run.

The general guide is 9 to 11 sq in per cf of box area for an aero port, 11 to 15 sq in per cf of box for a round port, and 13 to 18 sq in per cf of box area for square and rectangular ports, and these are per sub numbers, and only a starting point and will be different for all the different makes of subs out there, and some like a lot more port area than others so you will need to experiment with port sizes to come up with something that hits it perfectly. Most of the subs out there have been used by someone on here so you might just need to ask if they like more or less port area than the standard guide might be.

[ChevyBoy95]

People most of the time don't use software to tell them how much aero port they need, they used experience. Me personally, like to do a single 6in flared PSP aero port per 15 when I had 2 DC 15's on 2 Nendo 2kd's. Programs would say that has too high of a port velocity, but in real testing, I had zero port noise, and great response from about 22hz up to about 55hz. I even wrote the box specs down and saved them due to how much I liked the box.

[hispls]

Have you attempted to use an 8" port? What's holding you back? You rarely hear people complaining about too much port area being a problem.

Really I'm surprised a 6" with a good flare couldn't vent a pair of 10's without unusual noise but perhaps if you showed us a picture of the box or gave more details something would reveal itself.

[brent379]

Ooooooooooo I never knew that the square inch of port area per cube golden rule was per sub! I thought that was strictly just purr total amount of cubic feet lol. That would Definately change everything.

And see I originally was running 4 10s in about 5 cubes with 2 6" aeros and it did good! No port noise what do ever! Then when I decided to change it up and just see what 2 could do... I built a box that was 1.4 cubes after displacements and I figured if I used 2 6" aeros for all for tens then 1 6" aero should be plenty for just 2 10s and it failed. never understood why really.. in 1.4 cubes...a single 6 inch aero should have had about 10- 11sq in of port per cube per sub right?

And I don't have pics of the box. I ended up scrapping it and rebuilding it. I built another one at 1.4 cubes with an 11x3 slot port. And since then I've again changed it up and currently running a type r 12 in a series tuned 6th...just wanted to try a 6th out. And I'm going to be changing that here soon to lol

[brent379]

See I'm trying to get to that point where I don't need programs to tell me that stuff. I would love to be able to sit down and figure it all out on my own but I absolutely suck at math and the equations are beasts lol I've tried Idk how many times and have never got it right

[brent379]

I wonder if maybe was just bad port placement....

[4bannger]

I can't really speak for aero ports but when I have used slotted or square ports there is such a thing as "too" much port area. Isn't is true that you wanna keep it down enough to have back pressure? I know my last box I went for 16 per cube and hated it. Went down to 10 and loved it

[@Tripleb451]

Great info I was wondering the same thing. I still don't know which way I am going with my port.